1. Field of the Invention
The present invention relates to a sealed view finder in which an optical path of a finder optical system is partly or entirely closed.
2. Description of the Related Art
In a real image type view finder to be incorporated in a lens shutter type camera, etc., an optical element, such as a condenser lens is provided on a focal plane of an objective lens group or in the vicinity thereof, as shown in FIG. 5. In FIG. 5, a Condenser lens 63 is provided with a first surface 63a and a second surface 63b, on or in the vicinity of a focal plane of an objective lens group L1. If foreign matter such as dust contacts to the first or second surface 63a or 63b of the condenser lens 63, the foreign matter which is in the vicinity of the focal plane can be viewed in a focused state on an object image by a photographer. Hence, the foreign matter obstructs the object image.
A solution to this problem is to partially isolate the light path of the finder including optical elements from the surroundings. For instance, a roof mirror 61, the condenser lens 63, a pentagonal prism 67, and an ocular lens L2 are positioned within a sealed finder housing 51 which defines therein a closed optical path having a rectangular shape in a cross section perpendicular to the optical axis. Entrance and emission openings 53 and 54 of the finder housing 51 are closed or sealed by a first glass cover 58 and a second glass cover 59, respectively.
However, in this configuration, the roof mirror 61 is housed in the housing 51, and accordingly, the side wall of the housing 51 is located behind the roof mirror 61. Therefore, there is unused space between the side wall of the housing 51 and the roof mirror 61, as shown in FIG. 5.